In: Other
Lowest heat transfer coeffient is for ?
A) Boiling
B) Free Convection
C) Forced Convection
D) Condensation
And why ? and what is the second lowest
Here the answer is:
Lowest heat transfer coefficient is for free convection.
Reason:
Heat transfer coefficient can be said to be the total Watts of heat required to raise the temperature by 1-deg K. This would mean that the faster the heat transfer occurs, the higher the heat transfer coefficient.
According to the basic definition heat transfer rate is less for free convection as there is no external force involved in heat transfer for free convection..
So heat transfer coefficient is less for free convection.
Second lowest is forced convection.
Reason:
Here for forced convection there is external driving force for heat transfer, so it is higher than free convection.
And it is less than boiling and condensation because,
Boiling and condensation differ from other forms of convection, in that they depend on the latent heat of vaporization, which is very high for common pressures, therefore large amounts of heat can be transferred during boiling and condensation essentially at constant temperature.